Parking and maneuvering valve for trailers having a spring-loaded parking brake

ABSTRACT

The invention relates to a parking and maneuvering valve for trailers having a spring-loaded parking brake. The aim of the invention is to produce a braking system without a trailer braking valve. The invention provides a release unit, a parking unit and an emergency brake unit functionally assigned to the two units. The release unit, parking unit and emergency brake unit are interactively connected so that the parking unit convoys the pressure exerted by the reservoir of the trailer by the emergency brake unit or conveys the pressure exerted by the coupling head “reservoir” by the emergency brake unit to the spring-loaded parking brake system.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a parking and maneuvering valve for trailershaving a spring-loaded parking brake.

The design of the standard brake system for trailers is a prior artbrake system that is equipped with a spring-loaded parking brake that isin general complicated and expensive. A trailer brake valve is used thatis connected to a so-called combination release valve. In addition,there is a separate two way or shuttle valve that prevents stress on themechanical brake due to additional force from the service brake memberand the spring-loaded brake member on the trailer brake. This class ofbrake system is provided with two button control. That is, thecombination release valve works with two actuating buttons. When thetrailer is uncoupled and braked, the combination cylinder, whichcombines the diaphragm cylinder/spring-loaded cylinder of the servicebrake and parking brake, can be released by depressing both buttons andthus, the unbraked vehicle can be moved.

Given the above, the object of the invention is to simplify in such amanner the construction of trailer brake systems, equipped with aspring-loaded parking brake, that it retains the two button control andyet is inexpensive. In principle, it should be possible to put thetrailer into park position both in the coupled and uncoupled state evenif, as a consequence of short term or long term leakages, pressurelosses in the compressed air supply of the trailer must be accepted.

This problem is solved with the features according to the claimedinvention.

The simple construction of the valve unit, which eliminates theadditional use of a trailer brake valve, is achieved through acombination of release unit, parking unit, and emergency brake unit. Theemergency brake unit automatically reduces the speed of the trailer inthe event of a break in the supply line, not by means of the servicebrake of the trailer, but by means of the spring-loaded brake system, afeature that constitutes a significant contribution to the functionalityand reliability of the trailer brake system to the effect that duringemergency braking no compressed air supply is necessary to operate theservice brake and short or long term leakages in the compressed airsupply of the trailer do not have any negative effect on the brakingduring standstill. The module, comprising release unit, parking unit andemergency brake unit, forming preferably a valve block, has universalapplication. It can also be retrofitted. If the two button control iskept, then previously recognized advantages of the control mode andpossibilities can be retained.

Advantageous embodiments and improvements are described herein.

The invention is explained below by means of one embodiment withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 through 5 are individual sectional views, respectively, of theinventive valve block, comprising release unit, parking unit andemergency brake unit, in its circuit-related arrangement in a trailerbrake system with spring-loaded parking brake.

DETAILED DESCRIPTION OF THE DRAWINGS

The parking and maneuvering valve for trailers with a spring-loadedparking brake system is assembled, as depicted in FIGS. 1 to 5, as aso-called combination valve, comprising a release unit 1, a parking unit3, and an emergency brake unit 5.

The aforementioned components are connected so as to interact and serveto set the drive, park and maneuver positions of the trailer.

The release unit 1 exhibits a slider 7, which can be slid in a housing,with an actuating button 9. The release unit is connected by means of aline 11 to the coupling head “supply” 13, whereby the position-dependentlines 15 and 17 are monitored by means of the slider 7. The lines leadto the emergency brake unit 5 in the manner described below.

The parking unit 3 is in a comparable manner provided with a slider 21,which can be actuated by means of an actuating button 19 and whichmonitors lines 23 and 25, which lead to the emergency brake unit 5, andanother line 27. The line 27 leads over a shuttle valve 29 and a line 31to a spring-loaded brake member 33, which can form together with aservice brake member 35 a combined service brake and spring-loaded brakecylinder 37, or is provided as a stand alone member.

An EBS module 39 (electronic brake system) can be attached, as shown inFIG. 1 of the drawings, to the combined service brake and spring-loadedbrake cylinder 37, also called the combination cylinder. The EBS module39 is attached by means of a line 41 to the coupling head “brake” 43 ofthe trailer. In the coupled trailer, the service brake of thecombination cylinder is actuated or bled in a well-known manner by meansof the coupling head “brake” 43 and the following EBS module 39 and bymeans of a line 41. The aforementioned shuttle valve 29 prevents thecombination cylinder from overloading on the mechanical brake, since anoverlapping of the forces of the spring-loaded brake member and theservice brake member is ruled out. The shuttle valve 29 is not limitedto the illustrated structural position. That is, it can also beintegrated into the parking unit 3 in the attachment area of the line 27or the EBS module 39.

Inside the emergency brake unit 5 there is a piston 45, which is loadedover the line 15 by the supply pressure of the coupling head “supply” 13in the drawing according to FIG. 1, and which is slid, as depicted inFIGS. 1, 3, 4 and 5, into its bottom functional position under pressureload against the force of a spring 47. In the interior of the piston 45there is an inlet/outlet valve 49, which is formed by means of a valvebody 51, which can be slid against spring force; a valve seat 53, whichis stationary in the housing; and a valve seat 55, which moves with thepiston. The valve seat 53, which is stationary in the housing, interactswith the valve body 51 as the outlet valve 57, whereas the valve seat55, which can be moved with the piston, forms with the valve body 51 theinlet valve 59. The outlet valve 57 leads to an attachment 61, leadingto the atmosphere, whereas in its open position the inlet valve isconnected, as depicted in FIGS. 1 and 3, by means of the lineconnections to the spring-loaded brake member of the combinationcylinder.

The function of the inventive parking and maneuvering valve, comprisingthe release unit 1, the parking unit 3, and the emergency brake unit 5,is described below with reference to the different function charts ofFIGS. 1 to 5.

FIG. 1 depicts the operating state of the trailer in drive position, inwhich it is connected, thus coupled, to the towing vehicle. By means ofthe piston seal 63 of the piston 45, which is designed as the checkvalve, a supply tank 65, attached to the emergency brake unit 5, issupplied with compressed air from the towing vehicle by means of thecoupling head “supply” 13. As a consequence of the pressure load, thepiston 45 is in its bottom functional position, that is, in stopposition at,a stop 67 of the valve housing of the emergency brake unit.The inlet valve 59 is opened according to the drawing. That is,compressed air flows from the supply tank 65, after passing a checkvalve 69, through the inlet valve 59 into the line 23, attached to theparking unit. The actuating button 19 is located, as depicted in FIG. 1,in its upper position of the drive position, so that the line 23 isconnected to the line 27 and thus by way of the shuttle valve 29 to thespring-loaded brake member 33. Then the release chamber of thespring-loaded brake member of the combination cylinder is loaded withcompressed air, thus the spring-loaded or parking brake is released.Since the line 41 is without pressure, the combination cylinder isaltogether in release position. That is, the towing vehicle and thetrailer are in drive position when the brake system is released.

FIG. 2 of the drawings depicts the combination valve after uncouplingthe trailer from the towing vehicle. The actuating buttons 9 and 19remain in their positions. As a consequence of bleeding the line 15, thepiston 45 returns into its upper stop position under the effect of thespring 47. In this position the inlet valve 59 is closed; and the outletvalve 57, which monitors the connection to the attachment 61, is opened.The aforementioned connection by way of the lines 27, 23 and the outletvalve is opened, thus bled, so that the spring-loaded or parking brakebecomes effective. The line 41, connected to the coupling head “brake”43 is also bled as a consequence of the uncoupling, thus preventingadditional braking forces at the combination cylinder. In this operatingstate, the trailer is safely decelerated under the effect of theaccumulator spring of the spring-loaded brake member. As a consequence,any leakage of the supply tank 65 has no effect.

The aforementioned operating state also takes place when in the coupledtrailer there is a pressure loss in the supply line and a specificpressure of, for example, 2.5 bar, is exceeded. This state leads to anautomatic reduction in speed of the trailer.

FIG. 3 of the drawings depicts the operating state “maneuvering” in theuncoupled trailer. To this end, the actuating button 9 of the slider 7is slid to the top, whereas the actuating button 19 remains in itsposition, illustrated in FIGS. 1 and 2. In a pressureless line 11, thecompressed air flows out of the supply tank 65, after passing the checkvalve 69, into the line 17, over the release unit 1 into the line 15 anddrives the piston 45. As a consequence, said piston assumes theposition, illustrated in FIG. 1 of the drawings. In this position thereis a compressed air connection over the parking unit 3 to thespring-loaded brake member in such a manner that the accumulator springis pressurized and the parking brake is released. In the uncoupledtrailer, the line 41 is in turn without pressure so that the EBS module,feeding under relay effect the service brake member of the combinationcylinder, is not activated. Thus, the combination cylinder is in itsentirety released and the trailer can be moved, thus maneuvered.

If at this stage the trailer is connected to the towing vehicle, theposition, which corresponds to the drive position and is depicted inFIG. 1, is automatically reversed. When the coupling head “supply” 13 iscoupled to the corresponding coupling head of the towing vehicle, theslider 7 is pressurized. As a consequence, said slider is slid out ofthe position, shown in FIG. 3, in the downward direction to theposition, shown in FIG. 1. That is, it is slid as far as the stop. Thepressure conditions at the emergency brake unit 5 remain unchanged. Thatis, the piston 45, which was previously loaded over the line 17 and theline 15 with compressed air of the supply tank 65, remains in itsillustrated position, because when moving the slider 7, the piston 45 isno longer pressurized as described above, but by means of the couplinghead “supply” 13, as depicted in FIG. 1.

FIGS. 4 and 5 of the drawings depict the parking position of the trailerin the uncoupled state (FIG. 4) and in the coupled state (FIG. 5). Inthe position, depicted in FIG. 4, the actuating button 9 is located inthe maneuvering position, explained with reference to FIG. 3, whereasthe parking unit 3 is activated by actuating the actuating button 19,that is by moving the same into the parking position. As a consequenceof this actuation of the parking unit, the line 27 and therefore thespring-loaded brake member 33 is bled over the shuttle valve 29 and line31, whereby the line 27 is connected by way of the line 25 to theattachment 61, leading to the outside air. The spring-loaded brakemember 33 is activated by means of bleeding. That is, the parking brakeof the uncoupled trailer becomes effective.

It is possible to bleed the spring-loaded brake member 33, that isactivate the parking brake, even in a trailer that is coupled to thetowing vehicle, as illustrated by the positions in FIG. 5. In turn theactuating button 19 of the parking unit 3 is actuated, thus pulled outso as to point in the downward direction, so that the aforementionedbleeding of the spring-loaded brake member 33 occurs in the coupledstate. Should the driver actuate at this point in time the service brakeof the towing vehicle, a state that results in the activation, thuspressurization of the line 41, by means of the coupling head “brake” 43,then there is no negative effect on the combination cylinder owing tothe function of the shuttle valve 29. There are no additional forcesfrom the spring-loaded brake member and the service brake member, sincethe service brake actuation takes the place of the aforementionedspring-loaded brake actuation. The service brake pressure becomes activeby way of the shuttle valve 29 both in the spring-loaded brake member 33and in the service brake member 35. In the spring-loaded brake member 33the accumulator spring is released again, whereas in the service brakemember the service brake diaphragm or a similar actuating member ispressurized.

The position of the release unit 1 also changes in relation to theposition according to FIG. 3, since during coupling the release unit 1is loaded with compressed air of the coupling head “supply” 13 andcorrespondingly the slider 7 is moved in the downward direction of thestop into the position, which is depicted in FIG. 5 and corresponds tothe “drive position”. Both in the uncoupled and in the coupled state ofthe trailer, it is possible to reduce the speed of the trailer.

In the coupled vehicle, the check valve 69, integrated into the piston45, prevents automatic deceleration during a trip in the event of apressure drop in the supply tank 65, since the spring-loaded brakemember remains bled, thus remains released. The check valve 69 isprovided in this sense as the pressure safety unit between the supplytank and the spring accumulator.

As explained above, the shuttle valve 29 prevents an overloading of themechanical brake by means of the combination cylinder, since anoverlapping of the forces of the spring-loaded brake member and theservice brake member is ruled out.

Both the release unit 1 and the parking unit 3 can be provided with aforce threshold in one or in all positions. In this respect it can be aspring-loaded catch element, which during actuation must be overcome. Inthe parking unit 3 a known blocking unit can also be provided in thepark position.

The invention is not limited to the illustrated trailer brake systemwith a combined service brake and spring-loaded brake cylinder of thedesign, depicted in FIGS. 1 to 5. That is, the release unit, the parkingunit, and the emergency brake unit can also be realized in trailer brakesystems, in which the spring-loaded brake cylinder and the service brakecylinder are separated from each other, thus do not act on a commonpressure rod. In this case there is no need for a shuttle valve.Similarly the invention is not limited to the application of an EBSmodule of the illustrated type. The advantages of the describedcombination release valve with integrated emergency brake function canbe applied independently of the design of the valve, assigned to thebrake cylinder or the combination cylinder.

Table of Reference Numerals

1 release unit

3 parking unit

5 emergency brake unit

7 slider

9 actuating button

11 line

13 coupling head “supply”

15 line

17 line

19 actuating button

21 slider

23 line

25 line

27 line

29 shuttle valve

31 line

33 spring-loaded brake member

35 service brake member

37 combined service brake and spring-loaded brake cylinder

39 EBS module

41 line

43 coupling head “brake”

45 piston

47 spring

49 inlet/outlet valve

51 valve body

53 valve seat

55 valve seat

57 outlet valve

59 inlet valve

61 attachment

63 pistons seal

65 supply tank

67 stop

69 check valve

What is claimed is:
 1. Brake system for trailers, comprising: a parkingand maneuvering valve, which includes a release unit, a parking unit andan emergency brake unit, wherein a supply tank and a spring-loadedparking brake are attached to the parking and maneuvering valve, supplyand braking attachments, which are couplable to a towing vehicle brakesystem, wherein the supply attachment is connected to the release unit,and the brake attachment controls a service brake cylinder, and a firstactuating unit, which includes a first actuating member, assigned to theparking unit, wherein a) the supply tank is attached to the emergencybrake unit, and the emergency brake unit has an emergency brake valve,wherein to fill the supply tank, the supply attachment is connectablevia the release unit and the emergency brake valve to the supply tank;b) the spring-loaded parking brake is attached to the parking unit, andthe parking unit is connected to the emergency brake unit; c) a secondactuating unit includes a second actuating member, assigned to therelease unit; and wherein d) as a function of the switching position ofthe release unit and the parking unit and as a function of the brakesystem of the trailer, the spring-loaded parking brake is uncoupled orcoupled, pressurized or bled, in accordance with one of the drive,maneuvering or parking states.
 2. Brake system, as claimed in claim 1wherein: a) the parking unit is attached by way of a line to thespring-loaded brake member of the spring-loaded parking brake; b) thefirst actuating member of the parking unit comprises a first slider,which is provided with an actuating button outside the parking unit; andc) spaced over an outer periphery of the first slider are sealingelements, which in accordance with a switching position of the firstslider monitor the connection between the emergency brake unit and thespring-loaded brake member of the spring-loaded parking brake.
 3. Brakesystem, as claimed in claim 1, wherein: a) the emergency brake unitincludes a spring-loaded piston, which is pressurized from the supplyattachment via the release unit, when the supply and brake attachmentsare coupled, and is moveable into a first switching position against thespring tension under the influence of the supply pressure; b) the supplytank of the trailer is fed in such a manner via a sealing element, whichis located on the piston and acts as the check valve, that the supplytank is fillable with supply air when the release unit is attached tothe supply attachment; c) the emergency brake valve of the emergencybrake unit bears an inlet/outlet valve, which monitors in such a mannerthe connection between the supply tank and the parking unit, controllingin accordance with the position of the first slider the connection tothe spring-loaded parking brake, on the one hand, and on the other hand,the bleeding of the spring-loaded brake member that in the firstswitching position of the piston during pressurization of the same theinlet valve of the inlet/outlet valve is opened, whereas in the secondswitching position during subsequent uncoupling of the vehicle or linebreak due to a lack of pressurization of the piston, the bleedingconnection of the spring-loaded brake member over the parking unit whenthe inlet valve is closed occurs via the opened outlet valve.
 4. Brakesystem, as claimed in claim 1, wherein the second actuating member ofthe release unit comprises a second slider; and when the second slideris slid completely into the release unit and when the first slider isslid completely into the parking unit, a maneuver switching position isformed in such a manner that the spring-loaded braking member of thespring-loaded parking brake is pressurized and released over the openedinlet valve and the parking unit is pressurized with compressed air fromthe supply tank and released.
 5. Brake system, as claimed in claim 2,wherein the second actuating member of the release unit comprises asecond slider; and when the second slider is slid completely into therelease unit and when the first slider is slid completely into theparking unit, a maneuver switching position is formed in such a mannerthat the spring-loaded braking member of the spring-loaded parking brakeis pressurized and released over the opened inlet valve and the parkingunit is pressurized with compressed air from the supply tank andreleased.
 6. Brake system, as claimed in claim 3, wherein the secondactuating member of the release unit comprises a second slider; and whenthe second slider is slid completely into the release unit and when thefirst slider is slid completely into the parking unit, a maneuverswitching position is formed in such a manner that the spring-loadedbraking member of the spring-loaded parking brake is pressurized andreleased over the opened inlet valve and the parking unit is pressurizedwith compressed air from the supply tank and released.
 7. Brake system,as claimed in claim 4, wherein: a) when coupling the brake system of thetrailer, the second slider of the release unit is moveable, beginningfrom its maneuvering position, into a drive position via pressurepending at the supply attachment; b) the switching position of the firstslider, which belongs to the parking unit and is moved into themaneuvering position, remains unchanged in the drive position, wherebythe spring-loaded brake member is pressurizeable with compressed air forpurposes of releasing the brake; and c) when the first slider movesautomatically into the drive position, the pressurization of the pistonof the emergency brake unit that results by way of the supply tank inthe maneuvering position, is taken over by the direct pressurizationfrom the supply attachment.
 8. Brake system, as claimed in claim 5,wherein: a) when coupling the brake system of the trailer, the secondslider of the release unit is moveable, beginning from its maneuveringposition, into a drive position via pressure pending at the supplyattachment; b) the switching position of the first slider, which belongsto the parking unit and is moved into the maneuvering position, remainsunchanged in the drive position, whereby the spring-loaded brake memberis pressurizeable with compressed air for purposes of releasing thebrake; and c) when the first slider moves automatically into the driveposition, the pressurization of the piston of the emergency brake unitthat results by way of the supply tank in the maneuvering position, istaken over by the direct pressurization from the supply attachment. 9.Brake system, as claimed in claim 6, wherein: a) when coupling the brakesystem of the trailer, the second slider of the release unit ismoveable, beginning from its maneuvering position, into a drive positionvia pressure pending at the supply attachment; b) the switching positionof the first slider, which belongs to the parking unit and is moved intothe maneuvering position, remains unchanged in the drive position,whereby the spring-loaded brake member is pressurizeable with compressedair for purposes of releasing the brake; and c) when the first slidermoves automatically into the drive position, the pressurization of thepiston of the emergency brake unit that results by way of the supplytank in the maneuvering position, is taken over by the directpressurization from the supply attachment.
 10. Brake system, as claimedin claim 1, wherein the first and second actuating members comprisefirst and second sliders, respectively; and when the first slider ispulled out of the parking unit, the parking position of the trailer isswitchable in such a manner in both the maneuver position in accordancewith the retracted first slider and the drive position when the secondslider of the release unit has been pulled out that the spring-loadedbrake member is bleedable by way of the bleeding attachment of theemergency brake unit so that the parking position is possible in boththe uncoupled and in the coupled state of the brake system.
 11. Brakesystem, as claimed in claim 2, wherein the first and second actuatingmembers comprise first and second sliders, respectively; and when thefirst slider is pulled out of the parking unit, the parking position ofthe trailer is switchable in such a manner in both the maneuver positionin accordance with the retracted first slider and the drive positionwhen the second slider of the release unit has been pulled out that thespring-loaded brake member is bleedable by way of the bleedingattachment of the emergency brake unit so that the parking position ispossible in both the uncoupled and in the coupled state of the brakesystem.
 12. Brake system, as claimed in claim 3, wherein the first andsecond actuating members comprise first and second sliders,respectively; and when the first slider is pulled out of the parkingunit, the parking position of the trailer is switchable in such a mannerin both the maneuver position in accordance with the retracted firstslider and the drive position when the second slider of the release unithas been pulled out that the spring-loaded brake member is bleedable byway of the bleeding attachment of the emergency brake unit so that theparking position is possible in both the uncoupled and in the coupledstate of the brake system.
 13. Brake system, as claimed in claim 4,wherein when the first slider is pulled out of the parking unit, theparking position of the trailer is switchable in such a manner in boththe maneuver position in accordance with the retracted first slider andthe drive position when the second slider of the release unit has beenpulled out that the spring-loaded brake member is bleedable by way ofthe bleeding attachment of the emergency brake unit so that the parkingposition is possible in both the uncoupled and in the coupled state ofthe brake system.
 14. Brake system, as claimed in claim 7, wherein whenthe first slider is pulled out of the parking unit, the parking positionof the trailer is switchable in such a manner in both the maneuverposition in accordance with the retracted first slider and the driveposition when the second slider of the release unit has been pulled outthat the spring-loaded brake member is bleedable by way of the bleedingattachment of the emergency brake unit so that the parking position ispossible in both the uncoupled and in the coupled state of the brakesystem.
 15. Brake system, as claimed in claim 2, wherein there is acombined service brake cylinder and the spring-loaded parking brake,which is connected to a shuffle valve, which is attached, on the onehand, to the line, provided to pressurize and bleed, and also to a line,leading to the brake attachment, and which is provided for the purposeof preventing the spring-loaded parking brake and the service brakecylinder from having an additional braking pressure.
 16. Braking system,as claimed in claim 1, wherein a check valve, which acts as a pressuresafety unit for the spring-loaded parking brake, is located between thesupply tank and the inlet/outlet valve and opens in the direction of thesame.
 17. Brake system, as claimed in claim 1, wherein the combinedservice brake cylinder and spring-loaded parking brake cylinder iscontrolled via an EBS module when the brake attachment is coupled; andwherein the EBS module is fed via the supply tank.
 18. Brake system, asclaimed in claim 1, wherein the release unit and the parking unit arestructurally integrated with the emergency brake unit.